The invention relates to a semiconductor light emitting apparatus and its manufacturing method, and more particularly, to a so-called mold-type semiconductor light emitting apparatus having a light emitting device sealed with resin, the semiconductor light emitting apparatus having improved extraction efficiency of light from the mold resin to the air and its manufacturing method.
One of the typical semiconductor light emitting apparatuses is a semiconductor light emitting apparatus having a semiconductor light emitting device such as LED (light emitting diode) or LD (laser diode) sealed with mold resin. Many of the compound semiconductors constituting such a semiconductor light emitting device have refractive index in the light emission wavelength region as high as about 3.2 to 3.7. On the other hand, the mold resin has refractive index as low as about 1.5. For this reason, since light emitted from the light emitting area is incident from the compound semiconductor layer having high refractive index on the mold resin having low refractive index, it is totally reflected at the interface with the mold resin for incident angles greater than the critical angle. This causes a problem of decreased light extraction efficiency. In this respect, total reflection can be suppressed by roughening the surface of the compound semiconductor (e.g., Japanese Laid-Open Patent Application 2003-174191).
As described above, optical transmittance from the semiconductor light emitting device to the mold resin can be improved.
However, with respect to light extraction from mold resin to the air, the transmittance is restricted by the difference between their refractive indices. Thus there is a problem that the light extraction efficiency is still low.